Some Properties of the Solar Wind Turbulence at 1 AU Statistically Examined in the Different Types of Solar Wind Plasma

Abstract

AbstractA four‐plasma classification scheme is used to categorize the ACE solar wind data set into four types of plasma: (1) coronal‐hole‐origin plasma, (2) streamer‐belt‐origin plasma, (3) sector‐reversal‐region plasma, and (4) ejecta. The statistical properties of the solar wind fluctuations at 1 AU are analyzed for each of the four types of plasma in the years 1998–2008 using ACE magnetic field and plasma measurements. Between the four types of solar wind plasma there are subtle statistical differences in the spectral indices of (a) trace‐B, (b) trace‐v, (c) total energy, (d) magnetic intensity, and (e) plasma number density. Between the four types of plasma there are significant statistical differences (a) in the Elsässer inward and outward spectral indices, (b) in the outward imbalance, (c) in the Alfvénicity, (d) in the normalized vector‐B, vector‐v, magnetic intensity, and number density fluctuation amplitudes, (e) in the population of strong current sheets, (f) in the population of sudden velocity shears, (g) in the anisotropies of magnetic field and velocity fluctuations, and (h) in the parallel‐to‐B magnetic field fluctuation spectral index. It is argued that the four‐plasma categorization scheme is superior to a slow‐versus‐fast categorization for the study of turbulence and fluctuations in the solar wind.